• Korean Journal of Food Science and Technology
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• v.7 no.1
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• pp.37-42
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• 1975

The color intensity (Absorbance at 490nm) and the antioxidant effects of absolute and 90% ethanol extracts obtained from a Maillard-type browning reaction mixture (0. 5M glucose and 0. 5M glycine mixture, heated at $100^{\circ}C$) were determined. The color intensity of the absolute and 90% ethanol extracts were compared with the length of reaction time and the antioxidant effects of the extracts of both types were compared one another. The results obtained are as follows. 1. The color intensity of the absolute ethanol extracts remained almost unchanged as the browning reaction proceeded. The color intensity of the 90% ethanol extracts appeared to increase nearly in proportion to the length of reaction time. 2. The absolute and the 90% ethanol extracts seemed to possess significant antioxidant activity on the autoxidation of an edible soybean oil. which was kept at $45{\pm}0.5^{\circ}C$ for 21 days. It was noteworthy that the absolute ethanol extracts showed stronger antioxidant effects than those of the 90% ethanol extracts, which contained a far greater amount of brown-colored pigments. Since the PVs of the controls in both groups, after the end of the storage period, did not differ much from one another, the possibility of residual water playing some prooxidant role in the substrates containing the 90% ethanol extracts should be ruled out. Extracts of both types obtained at earlier stages of the brownig reaction demonstrated less but comparable antioxidant activity to that of extracts taken at later stages of the reaction. 3. The results of the present study appeared to suggest that the effective antioxidant compounds, produced in the Maillard-type browning reaction, were probably intermediate products such as reductones formed at fairly earlier stages of the browning reaction.

• The Plant Pathology Journal
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• v.20 no.2
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• pp.142-146
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• 2004

Woody plant tissues contain great amounts of phenolic compounds and polysaccharides. These substances inhibit the activation of reverse transcriptase and/or Taq polymerase in RT-PCR. The commonly used multiple-step protocols using several additives to diminish polyphenolic compounds during nucleic acid extraction are time consuming and laborious. In this study, sodium sulfite was evaluated as an additive for nucleic acid extraction from woody plants and the efficiency of RT-PCR assay of commercial nucleic acid extraction kits and small-scale dsRNA extraction was compared. Sodium sulfite was used as an inhibitor against polyphenolic oxidases and its effects were compared in RNA extraction by commercial extraction kit and small-scale double-stranded RNA (dsRNA) extraction method for RT-PCR. During nucleic acid extraction, addition of 0.5%-1.5%(w/v) of sodium sulfite to lysis buffer or STE buffer resulted in lighter browning by oxidation than extracts without sodium sulfite and improved the RT-PCR detection. When commercial RNA extraction kit was used, optimal concentrations of sodium sulfite were variable according to the tested plant. However, with dsRNA as RT-PCR template, sodium sulfite 1.5% in STE buffer improved the detection efficiency of Apple chlorotic leaf spot virus (ACLSV) and Apple stem grooving virus (ASGV) in fruit trees, and reduced the unspecific amplifications signi-ficantly. Furthermore, when viruses existed at low titers in host plant, small-scale dsRNA extractions were very reliable.

• Journal of Nutrition and Health
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• v.17 no.1
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• pp.60-67
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• 1984

Inhibiting action of sulfur dioxide $(SO_{2})$ on enzymatic discoloration was investigated with crude enzyme preparations from homogenized tissues or sliced disks of raw potato tubers. $SO_{2}$ appeared to inhibit the formation of dopachrome in a competitive manner. At insufficient concentrations of $SO_{2}, the formation of dopachrome was reinitiated as time elapsed. The present results suggested that $SO_{2}$ would form an additional compounds with certain intermediate during the course of enzymatic browning and delay the enzymatic discoloration. To inhibit the production of dopachrome in sliced disks of raw potato tubers, much higher concentrations of $SO_{2}$ were required than homogenized tissues.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.502-506
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• 2005

Three EGCG analogues were synthesized by the acceptor reaction of a glucansucrase from Leuconostoc mesenteroides B-1299CB with EGCG and sucrose. The transfer products was purified using Sephadex LG-20 column chromatography and high performance liquid chromatography (HPLC). EGCG-G1 and EGCG-G2 were novel compounds for the first time reported in this paper. EGCG glycosides showed similar or slower antioxidative effects according to their structures $(EGCG{\geq}EGCG-G1>EGCG-G1'>EGCG-G2)$. However, the water solubilities of the EGCG-G1, EGCG-G1' and EGCG-G2 were 52, 76 and 140 times higher than that of EGCG. Furthermore, they showed more browning resistance against UV irradiation than EGCG.

• Korean Journal of Pharmacognosy
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• v.19 no.3
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• pp.201-207
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• 1988

Samples of red ginseng, which had been manufactured and packaged by the Korean Monopoly Corporation, were stored at ambient temperatures and humidities ($12{\sim}28^{\circ}$ and $55{\sim}68$ percent) for one to nine years to examine their overall quality stability. The proximate compositions, contents of 50% ethanol and water extracts of the samples and the TLC and HPLC patterns of ginsenosides in the samples remained almost unchanged in all cases. The lipids and fatty acids in the samples, which are otherwise susceptible to oxidation, were stable judged on the basis of the changes of the TLC and GLC patterns of the lipids and fatty acids. It was also found that polyunsaturated fatty acids such as linoleic(C18:2) and linolenic and(C18:3) present in the samples had been very stable during the long storage periods. It, therefore, seems that the autoxidations of the lipid and fatty acids of red ginseng were prevented by antioxidative compounds which will be progressively formed in red ginseng through non-enzymatic browning reactions during manufacturing process and long-term storage.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1253-1253
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• 2001

The ability to accurately assess wine quality is important during the wine making process, particularly when allocating batches of wines to styles determined by consumer requirements. Grape payments are often determined by the quality category of the wine that is produced from them. Wine quality, in terms of sensory characteristics, is normally a subjective measure, performed by experienced winemakers, wine competition judges or winetasting panellists. By nature, such assessments can be biased by individual preferences and may be subject to day-to-day variation. Taste and aroma compounds are often present in concentrations below the detection limit of near infrared (NIR) spectroscopy but the more abundant organic compounds offer potential for objective quality grading by this technique. Samples were drawn from one of Australia's major wine shows and from BRL Hardy's post-vintage wine quality allocation tastings. The samples were scanned in transmission mode with a FOSS NIR Systems 6500, over the wavelength range 400-2500 ㎚. Data analysis was performed with the Vision chemometrics package. With samples from the allocation tastings, the best correlations between NIR spectra and tasting data were obtained with dry red wines. These calibrations used loadings in the wavelengths related to anthocyanins, ethanol and possibly tannins. Anthocyanins are a group of compounds responsible for colour in red wines - restricting the wavelengths to those relating to anthocyanins produced calibrations of similar accuracy to those using the full wavelength range. This was particularly marked with Merlot, a variety that tends to have relatively lower anthocyanin levels than Cabernet Sauvignon and Shiraz. For dry white wines, calibrations appeared to be more dependent on ethanol characteristics of the spectrum, implying that quality correlated with fruit maturity. The correlations between NIR spectra and sensory data obtained using the wine show samples were less significant in general. This may be related to the fact that within most classes in the show, the samples may span vintages, glowing areas and winemaking styles, even though they may be made from only one grape variety. For dry red wines, the best calibrations were obtained with a class of Pinot Noir - a variety that tends to be produced in limited areas in Australia and would represent the least matrix variation. Good correlations were obtained with a tawny port class - these wines are sweet, fortified wines, that are aged for long periods in wooden barrels. During the ageing process Maillard browning compounds are formed and the water is lost through the barrels in preference to ethanol, producing “concentrated” darkly coloured wines with high alcohol content. These calibrations indicated heaviest loadings in the water regions of the spectrum, suggesting that “concentration” of the wines was important, whilst the visible and alcohol regions of the spectrum also featured as important factors. NIR calibrations based on sensory scores will always be difficult to obtain due to variation between individual winetasters. Nevertheless, these results warrant further investigation and may provide valuable Insight into the main parameters affecting wine quality.

• Journal of the Korean Society of Food Science and Nutrition
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• v.12 no.4
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• pp.316-322
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• 1983

In order to obtain elementary data of enzymatic browning of apples and apple products and to examine effectively inhibitory method of browning, we extracted polyphenol oxidase (EC 1.10.3.1) from apple (Ralls Janet) and investigated its general properties. The optimum conditions for the enzyme reaction were pH 6.0 and temperature of $30^{\circ}C$. The enzyme was very stable at pH 4.0, and at the range of pH 5.0-9.0 its activity was above 80% compared with pH 4.0. The enzyme was very stable by heating at $40^{\circ}C$ for 1 hour, and almost 50% of enzyme activity was lost by heating at $60^{\circ}C$ for 30 minutes. The polyphenol oxidase activity was enhanced by the addition of $Cu^{2+}$ and $Mn^{2+}$, respectively, meanwhile $Na^+$, $Hg^{2+}$ and $Co^{2+}$ inhibited the enzyme activity. The enzyme activity was greatly decreased in the presence of inhibitors such as cysteine, sodium metabisulfite and ascorbic acid. The polyphenol oxidase greatly catalyzed the oxidation of o-diphenols such as chlorogenic acid and catechol, which suggests that main substrate of polyphenol oxidase is o-diphenol compounds.

• Journal of the Korean Society of Food Culture
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• v.28 no.1
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• pp.78-88
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• 2013

Marinated beef galbi is a traditional Korean dish cooked with soy sauce, pear juice, onion, sesame oil, and sugar. However, there are many differences in beef galbi, including flavor and physicochemical aspects, depending on cooking conditions. Therefore, the physicochemical characteristics of marinated beef galbi prepared through various recipes was evaluated for its effects on pH, texture, aging, proteolysis, heating conditions, cooking time, and flavor compounds (pyrazines, IMPs, or FAAs). There were significant differences in salt concentration (0.8~3.03%), pH (4.89~6.22), and solid soluble contents (1.34-6.31 Brix) between recipes in this study. In the Pearson assay for sensory evaluation, overall preference correlated well with texture (a well-known sensory attribute in meat evaluation). Controlling the pH of meat through soaking in lemon solution, alkali water, phosphate, and baking powder solution, improved water holding capacity as much as 9 to 15% compared with the control. The myofibril index (MFI) of marinated meat stored at $4^{\circ}C$ increased 32% with 24 hours of aging and reached 39% at 48 hours of aging, and its fragmentation was observed through microscopy. SDS-PAGE showed hydrolysis of acid-soluble collagen by the pear juice, possibly related to meat tenderness. On the basis of surface temperature, the cooking time was estimated to be 8 minutes with pan heating at $170^{\circ}C$, 6 minutes at $270{\sim}300^{\circ}C$, and 4 minutes with charcoal at $700{\sim}900^{\circ}C$. Different pyrazine compounds, such as 2-methyl-3-phenylpyrrol(2,3-b) pyrazine (the typical product of the browning reaction) was mainly detected, and IMP (one of the main taste compounds in beef) was in higher amounts with the charcoal treatment, potentially related to its flavor preference among treatments. Our results demonstrate an effective case study and cooking system for beef galbi.

• Korean Journal of Food Science and Technology
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• v.23 no.4
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• pp.414-419
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• 1991

Polyphenol oxidase from Jerusalem artichoke(Helianthus tuberosus L.) tubers was partially purified by precipitation with ammonium sulfate, followed by gel filtration on Sephadex G-100. The enzyme showed maximal activity at pH 6.5 and $4^{\circ}C$. Kinetic studies indicated $K_{m}$ value of 3 mM for catechol and activation energy of 72.6 kcal/mole. As for substrate specificity of polyphenol oxidase the enzyme showed high affinity towards diphenol compounds, but not towards monophenols. The enzamatic browning was completely inhibited at 1 mM concentration of L-ascorbic acid, sodium hydrosulfite and L-cystein(HCl). The activity of polyphenol oxidase in 0.1 M potassium phosphate buffer(pH 6.5) was fairly stable for a week at $4^{\circ}C$, while it decreased remarkably at $25^{\circ}C$.

• Preventive Nutrition and Food Science
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• v.2 no.4
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• pp.285-290
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• 1997

Previously, a 50% aqueous methanol extract of Galla rhois was shown to be the most potent tyrosinase inhibition activity with an {TEX}$IC_{50}${/TEX}(the concentration causing 50% inhibition of tyrosinase activity) of 0.2mg/ml of 205 crude drug extracts. To isolate tyrosinase inhibitors, the methanol extract was evaporated to a small volume in vacuo, and then partitioned stepwise with benzene and ethyl acetate(EtOAc). the EtOAc fraction was solubilized in 10% MeOH solution, and then fractionated successively by Diaion HP-20 and Sephadex LH-20 column chromatography, and preparative HPLC. Three phenolic compounds were isolated, and characterized as gallic acid(GA), methyl gallate(MG) and 1,2,3,4,6-penta-O-galloyl-$\beta$-D-glucose(PGG) by UV, IR, {TEX}${1}^H${/TEX}-&{TEX}${13}^C${/TEX}-NMR, and FAB-MS spectroscopy, PGG({TEX}$IC_{50}${/TEX}=50$\mu\textrm{g}$/ml) showed a considerable inhibitory effect against mushroom tyrosinase, while GA({TEX}$IC_{50}${/TEX}=1.6mg/ml) and MG({TEX}$IC_{50}${/TEX}=234$\mu\textrm{g}$/ml) did not show an appreciable effect. Meanwhile, MG inhibited greatly melanogenesis in a murine melanocyte cell line, Mel-Ab. MG and PGG showed typical noncompetitive inhibition patterns against mushroom tyrosinase. These results suggest that PGG and MG may be potentially useful as either anti-browning or anti-melanogenic agents in foods and cosmetics.